I had a sight glass blow out when I started my bike this morning. I bought a new glass at the local shop, along with a spring steel retaining ring that I don't recall being there before. Most likely the reason for the glass blowing out in the first place.

So now I'm trying to install the new glass and I clean up the seat where it fits, oil up the new glass, get my soft mallet and give 'er a tap or two. That works ok, but it's still not flush in the seat. OK, let's get a little more aggressive - a wood block and a hammer. I tap, tap some more working around the edges. Oops, the glass cracked! Damn! Ok, now since the glass is cracked and I'll have to get another one, I'll go ahead and tap this thing in with a screwdriver to get it to seat all the way in. Hmmm, doesn't seem to go any further and I still have this retaining ring that needs to be installed.

I got the broken new one out of the seat and have done some measuring. I don't see how any retaining ring can fit over theglass and I don't see any groove for the ring to fit any anyway.

I told the parts guy that it was a '99 RT, and he looked it up on the computer and gave me the ring with the new glass.

Am I nuts or is the sight glass just a press fit on a '99?

Any suggestions?

Thanks,Mark

I suggest that the parts guy heard "9" and didn't listen for the rest. I bet you have a sight glass and retaining ring for a hexhead, not an oilhead. I don't know the dimension for the later motors, but if it is a bit larger than the oilhead glass, that would explain why you had trouble getting it all the way in.Go back and get the right one.......I don't know what you will work out for the cost of the wrong (And broken) one, but believe me, if you have the right one, you can install it yourself. Before you put it in, select a socket that is just a bit smaller diameter, and use that to keep it square to the hole going in. Good Luck!

I have a new sight glass that I hold as a spare for the K, yet the K is unique in that when changing the oil/filter, one can actually remove the glass without damage. Since they have a metal backing with holes punched in it, what's done on the K is to use a long screw driver inserted up through the oil filter sealing cover.

Angled from there, using a hammer, slightly begin tapping on the metal interior of the glass. A few taps in different locations will eventually pop the whole thing out. When it's out, and to "clean it up", a paper towel, rolled to a point is inserted into the various holes through the metal backing. Once the towel is inside, dental tools are used to swipe the inner face of the glass with the towel.

A few rotations are required, but after due diligence, the glass is as clean as new, and ready to be re-installed. (A proper sized OD Socket works just sweet, and gentle, even tapping does the trick.) I've done this now twice with the same glass, no problems on the K.

Too bad the access to this little trick is not available on the R.

Haven't actually checked the part numbers yet, but it looks like the two are the same for the '85 K and the '96 R.

1. Put new sight glass in freezer overnight (optional)2. Get a wooden dowel slightly smaller than the o.d of the sight glass (Home Depot PN: 1-3/8 wooden closet hanger rod $1.49 + tax)3. Align and hand press the new glass into the seat. Use thumb pressure to get an even start all around the seat.4. Center the dowel on the glass rubber edge and tap gently until seated.5. Add oil and ride until operating tempature is reached.6. Check for leaks and proper oil level on center stand.

I'm not going to get involved in the 'shop vs. dyi' argument but I will say that I am glad that I did this myself, even if I did have to buy 2 sight glasses. Due to the BMW design flaw (my opinion) of this part (repaired with the retaining ring for the 1200s) this may be a recurring problem for my 1100. I now know how to fix this problem and will carry a spare glass as soon as I see any weeping on my new one.

I'm just real glad this happened im my driveway, not at 75 mph on the freeway. I would just hate to see that oil pressure light come on...

On the other hand, if you get the feel for driving in the sight glass using a similarly sized socket and lightly tap with a mallet, then you can carry one with you and if you DO lose one on the road can get back on the road yourself.

I lost one a while ago, unfortunately didn't realize it in time. BUT, from what I've read watch for and replace it at ANY sign of weeping or seeping around the glass, or when the glass starts to get heavily discolored. Had I known that, I wouldn't have a damaged engine now...

I'm just real glad this happened im my driveway, not at 75 mph on the freeway. I would just hate to see that oil pressure light come on...

Fortunately all that happens is a relatively small amount of oil is blown out of the hole, over your leg/boot and bike. The bottom of the sight glass hole is way above the minimum required level of oil for safe running and, with the engine running, the oil level drops below the glass anyhow.

"No man ever got very high by pulling other people down. The intelligent merchant does not knock his competitors. The sensible worker does not knock those who work with him. Don't knock your friends. Don't knock your enemies. Don't knock yourself." Alfred Lord Tennyson

" Fortunately all that happens is a relatively small amount of oil is blown out of the hole, over your leg/boot and bike. The bottom of the sight glass hole is way above the minimum required level of oil for safe running and, with the engine running, the oil level drops below the glass anyhow."

Absolutely untrue. As people here and on the RS forum and on the BMWBMW forum can attest.If you see ANY weeping from around the sight glass, replace it. Do not ride to the end of the block or the store or anywhere else. Replacing the sight glass takes no more than a few minutes, takes no real skill, and is a lot cheaper than rebuilding a motor when the rod bearings fail...which they can in an absolute heartbeat if you are riding at night and don't instantly realize the darn thing has blown out.

...which they can in an absolute heartbeat if you are riding at night and don't instantly realize the darn thing has blown out.

I've never tried it myself () so I'm not calling anyone right or wrong, but one would have to lose a lot of oil to starve the engine to the point of damage, at least a couple of quarts. Do you really lose that much oil that quickly if the sight glass goes..?

...which they can in an absolute heartbeat if you are riding at night and don't instantly realize the darn thing has blown out.

I've never tried it myself () so I'm not calling anyone right or wrong, but one would have to lose a lot of oil to starve the engine to the point of damage, at least a couple of quarts. Do you really lose that much oil that quickly if the sight glass goes..?

There is a lot of pumping of air going on by design in the crankcase of a boxer......I would imagine that the oil would exit pretty quickly through a 1.5" hole.